Currently, a trend of society is changing from conventional small-variety mass production to large-variety small-quantity production. In the production field of publications represented by books, pamphlets, magazines, and newspapers, too, large-variety small-quantity production using a business-purpose digital printer has begun to receive attention, after going through a period of small-variety mass production using a high-speed offset rotary press.
As one example of a digital printer, an inkjet type printer that prints by jetting ink onto a paper by heat or pressure, is known. Moreover, in such a printer, a printer comprising a plurality of print heads corresponding to a plurality of colors (for example, cyan (C), magenta (M), yellow (Y), and black (K)), is known.
In the above-mentioned inkjet type printer, a carriage system in which a plurality of printing color portions (for example, the previously described four color portions of C, M, Y, and K) are disposed gathered into one in a shuttle type print head, and printing is performed on a sheet, is known. Said system is suitable for depiction of a fine image. Moreover, as another system, a single-pass system in which, with respect to a continuous paper moving in one direction, a plurality of single color printing-dedicated print heads are disposed so as to cover a paper width in a paper width direction thereby forming a print head group, and furthermore, a plurality of printing color portions (for example, the previously described four color portions of C, M, Y, and K) of the above-mentioned single color printing-dedicated print head groups are disposed in a moving direction of the continuous paper, is known. Said system is suitable for high-speed printing.
When printing image data in the above-mentioned business-purpose digital printer, a data amount to be processed is extremely large compared to a data amount in general household and office printing, hence a long time is required for processing. Therefore, conventionally, various kinds of image processing such as so-called rasterization processing (RIP: Raster Image Processing), four color separation processing, tonal steps conversion processing, and rearrangement processing of data corresponding to placement of ink head, were performed prior to printing.